GB2118626A

GB2118626A - Suction chambers for fans

Info

Publication number: GB2118626A
Application number: GB08308730A
Authority: GB
Inventors: Olli Juhani Pukkila
Original assignee: Nokia Oyj
Current assignee: Nokia Oyj
Priority date: 1982-04-05
Filing date: 1983-03-30
Publication date: 1983-11-02
Also published as: SE459756B; FI821186L; FI77304C; US4540338A; SE8301825L; SE8301825D0; FI77304B; FI821186A0; GB2118626B

Description

1

GB 2 118 626 A 1

SPECIFICATION A suction chamber in a fan

The present invention relates to a suction chamber in a fan, the upper section of that wall of 5 the chamber which faces the suction inlet being parallel to the wall containing the suction inlet, but its lower section being inclined towards the latter side.

In fans it is sometimes necessary, owing to 10 shortage of space, cost of making conduits, etc., to direction the air or gas conduit to the suction inlet of a fan in a direction which is perpendicular to the axis of the fan. If the conduit is connected to the suction inlet by means of a pipe bend, the bulk of 15 the air will flow along the outer wall of the bend, whereby the impeller is loaded asymmetrically. In this case the fan will not achieve the pressure and the volume flow according to the calibration values, and its efficiency is also crucially lowered. 20 In certain cases the measured increase in power consumption has been up to 60%.

Attempts have been made to eliminate this disadvantage by developing suction chambers for fans. It is virtually necessary to use a suction 25 chamber in two-inlet fans, in which air flows via two suction chambers and two suction cones to two impellers which suck in air from opposite directions and further into one mutual casing.

Such fans are used mainly when the volume flow 30 is so great that two single-inlet fans would be needed.

There are power losses even in a suction chamber, and attempts have been made to eliminate them by making the chamber conical. 35 Furthermore, attempts have been made to reduce power losses by placing a baffle plate or guide vanes in the chamber.

Even in these, relatively complicated suction chamber structures, which are difficult to 40 manufacture, the power loss is 4—10% of the total power consumption of the fan within the conventional operating range, depending on the manufacturer, the fan type, and the location of the operating point on the performance curve. Since 45 suction chambers are used most in large fans, the power losses in question are considerable.

In the present invention, the characteristics of which are given in the accompanying claim, the power loss of the suction chamber is only 50 0.5—2.5% of the nominal power, depending on the fan type and the location of the operating point on the performance curve. The manufacturing cost of the suction chamber according to the invention is considerably lower 55 than the manufacturing cost of known suction chambers, which are more difficult to manufacture. It is not necessary to round or bevel the corners, nor is it necessary to place baffles or guide vanes in the chamber. In spite of this, the 60 power loss is considerably less than in known suction chambers.

One embodiment of the invention is described below with reference to the accompanying drawing.

65 Figure 1 shows a known two-inlet fan with its suction chambers, and Figures 2a—c depict known suction chamber structures. Figure 3 depicts a side view of a suction chamber according to the invention, and Figure 4 the same 70 as seen from the suction-inlet side, but with the connecting part left out.

In the known two-inlet fan according to Figure 1, air flows via two suction chambers 1 and two suction cones 2 to two impellers 3 sucking in 75 air from opposite directions, and further into one mutual casing 4.

Figure 2 depicts known basic models of suction chambers. Figure 2a shows, as seen from the suction-inlet side, a chamber with a beveled lower 80 section. Figure 2b shows respectively a chamber the lower section of which is rounded and in which a baffle 5 has been placed. In Figure 2b there is, in addition, a conical structure indicated by dotted lines 6. Figure 2c shows a side view of a 85 suction chamber provided with guide vanes 7.

In the embodiment according to the invention in Figures 3 and 4, A indicates the width of the suction chamber 1, B the depth of its upper section, C its bottom wall, and D the diameter of 90 the suction inlet. The slanted lower section 9 of the wall opposite the suction inlet 8 is about 2/3 of the height of this wall. The angle formed by the lower section and the horizontal plane is indicated by a.

95 Depending on the fan type and the position of the operating point on the performance curve, A, B, C and D must, according to the invention, be as follows in proportion to A:

B = 0.35-0.38 X A

100 C = 0.14-0.18 X A

D = 0.42 - 0.50 X A •

Furthermore, the angle a must be 67—78°. In this case the suction chamber can be made angular, without rounding or beveling, by selecting 105 a suitable length for it, so that the wall which contains the suction inlet 8 is rectangular,

whereby a high efficiency is achieved, the power loss being only 0.5—2.5% of the nominal power.

The suction chamber shown in the drawing is 110 intended for use in connection with centrifugal fans, but the suction chamber according to the invention can also be used in connection with other fans.

Claims

115 1. a suction chamber (1) in a fan, the upper section of that wall of the chamber which is opposite the suction inlet (8) being parallel to the wall which contains the suction inlet, but its lower section (9) being slanted towards the latter wall, 120 characterized in that the corners of the suction chamber (1) are angular, without rounding or beveling, and that its wal' containing the suction inlet (8) is rectangular, that the depth (B) of the upper section of the chamber is 0.35—0.38 times

2. A suction chamber substantially as herein described and shown in the accompanying drawing.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1983. Published by the Patent Office 25 Southampton Buildings. London, WC2A 1AY, from which copies may be obtained.

2

GB 2 118 626 A 2

the width (A) of the chamber, its bottom wall (C) is 0.14—0.18 times the width (A) of the chamber,

and the diameter (D) of its suction inlet is 0.42—0.50 times the width (A) of the chamber, 10 5 and that the lower section (9) of that wall which is opposite the suction inlet (8) is at an angle (a) to the horizontal plane, the size of the angle being 67—78°.